"SAN filers address the problem of provisioning enterprise file services in SANs," explains Peter Tarrant, ONStor's vice president of marketing. They do so through a combination of proprietary hardware and software.

While at first glance ONStor's SAN filer may look like a NAS "head" or gateway, analysts say that it differs in terms of features and the services it provides.

"Basically, there are two types of SAN-NAS gateways: those based on Microsoft's Windows Storage Server 2003 and those that aren't," says John Webster, a senior analyst with the Data Mobility Group consulting firm. "The Microsoft players are essentially looking for ways to sell more of something else they have in their product portfolio [e.g., disk storage], while non-Microsoft players tend to look at the gateway opportunity as more strategic [i.e., as a way to propagate various file services within a SAN]."

The FS4400 is certified with disk arrays from Hewlett-Packard, IBM, LSI, and Sun and has been tested in labs with EMC Clariion and Symmetrix arrays.

Analysts say that SAN-NAS gateways that run storage applications may eventually compete with intelligent switches.

It's all about the application and data and how you access that data in the SAN fabric, explains Webster. "Intelligent switches move data at the block level, and now there's a file-based way of doing that."

Over the past year, a number of switch vendors, including Brocade, Cisco, MaXXan, and McData, have detailed plans and product road maps for moving applications off hosts and subsystems and into switches in the SAN fabric. Doing so, proponents contend, will enable users to centralize and consolidate storage management and provisioning, replicate data among heterogeneous storage devices, and possibly lower management costs.

While the SAN filer could be integrated into an intelligent switch, ONStor officials say that it is too early to tell whether this will happen. "It remains to be seen whether switch vendors will [see this technology] as an incremental value-add and differentiator," says Tarrant.

In a recent InfoStor reader survey, 44% of the respondents said they would prefer to run storage applications on fabric switches, while 33% prefer disk arrays and 23% voted for host-based applications. The survey did not include storage gateways of any type.

ONStor's SAN filer serves files on the LAN (via four Gigabit Ethernet ports); all data, including metadata, journal data, and user data, is stored as a single storage pool on SAN-attached disk, which is managed by the ONStor file system. Up to four SAN filers can be pooled together into a cluster, with support for up to 40 petabytes of shared capacity, 400 file systems, and 140,000 I/Os per second.

Filers have concurrent access to all data at all times, which means users can back up data while applications are running. The configuration provides for high levels of availability (file services migrate among filers to ensure continuous availability) and redundancy; easy provisioning and load balancing among SAN resources; and quick restores, according to ONStor officials.

The FS4400 works with Tivoli and Veritas storage management software, as well as Brocade, Cisco, and McData switches. It is priced from $85,000 and is available through six resellers: AC Technology, Champion Solutions Group, Evolving Solutions, Key Information Systems, Maxium Solutions, and Micro Strategies.

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